The proposed projects concern the physiology of nerve cells in the brain and spinal cord of lower vertebrates. Excitation of individual Muller and Mauthner neurons in the lamprey by activity in the lateral line system will be tested. Conduction velocity of unmyelinated axons will be determined as a function of diameter after dye injection. The responses of interneurons in the isolated spinal cord of the lamprey to bath-applied acidic amino acids will be measured. The physiology of the Mauthner cell in bullfrog tadpoles and of the vestibulo-ocular reflexes in newts will be investigated with intracellular recordings in isolated preparations.